Left ventricular (LV) volumes are important prognostic indices in patients with heart disease. Although several methods can evaluate LV volumes, most have important intrinsic limitations. Real-time three- dimensional echocardiography (RT3D echo) is a novel technique capable of instantaneous acquisition of volumetric images. This study was undertaken to validate rapid LV volume calculations with RT3D echo and to determine their usefulness in cardiac patients. Initially, we reported the results obtained in 25 patients. During the course of these studies, it was apparent that an important number of patients had suboptimal endocardial border definition to allow for reliable volume calculation. We therefore decided to modify the protocol to include the injection of EchoGen, a contrast agent for intravenous injection that opacifies the left ventricular cavity and thus enhances endocardial border resolution. We have so far studied 86 patients with contrast injection that have yielded 71 evaluable patients. We will continue with patient accrual to reach a total of 75 evaluable patients before analyzing the correlation between RT3D echo and MRI in these patients. - real-time three-dimensional echocardiography (RT3D echo), magnetic resonance imaging (MRI) - Human Subjects